Technical Field
The present invention concerns a process for the production of a pylon segment of a concrete pylon of a wind power installation and a shuttering for production of such a pylon segment.
Description of the Related Art
Wind power installations, in particular those with a horizontal rotor axis as shown in FIG. 1, are nowadays enjoying increasing popularity.
Such wind power installations have a pod having an aerodynamic rotor. That pod with rotor can be of a weight of far more than 100 t (metric ton), depending on the size of the respective installation. The pod is supported on a pylon which can be in the form of a concrete pylon or a steel pylon and which has to carry the load of the pod and transmit it to a foundation. That load includes a load due to the weight of the pod and a load because of the wind pressure on the rotor in operation of the wind power installation.
Concrete pylons of wind power installations are typically made up of pylon segments, namely precast concrete parts of steel reinforced concrete. In that way they are fundamentally different from concrete pylons which are constructed from so-called on-site concrete, that is to say directly on site by means of a climbing shuttering or formwork, as is usual for example with television towers. In that respect the demands made on a concrete pylon of a wind power installation are different from another concrete pylon or tower. One of the specific demands is also the wind loading which has already been described above on the rotor, and thus on the pod and accordingly on the head of the pylon.
In accordance with a form of a wind power installation the pylon converges conically from below from its foundation upwardly towards its head. The pylon segments which are placed in superposed relationship for that purpose are to be appropriately adapted to each other at the junction locations. That involves in particular the shape and diameter of the segments in question in the region in which they are placed one upon the other. If a deviation between two segments to be placed one upon the other is excessively great here the concrete pylon in question can no longer be produced with an adequate manufacturing quality. At least one of the pylon segments to be assembled is then to be sorted out as reject and replaced by a suitable segment of better dimensions which in particular are more accurately observed. At least one shuttering used for production of the reject pylon segment has to be suitably modified or replaced. Sorting out such a reject pylon segment and possibly replacing a shuttering which has been used gives rise to unnecessary costs and can lead to a time delay when constructing a wind power installation.
A conically converging wind power installation pylon composed of a multiplicity of pylon segments, namely precast concrete parts, requires a correspondingly large number of different pylon segments. Those different pylon segments require a corresponding number of shutterings, that is to say formworks for pouring the respective concrete pylon segment. If wind power installations of differing size are produced then that needs concrete pylons of correspondingly different sizes and accordingly the number of necessary pylon segments and necessary shuttering arrangements increases. In particular when involving larger pylons and a larger number of different pylons the number of different pylon segments and shutterings required rises to a corresponding degree and can become a logistical and/or organizational problem in the enterprise in question dealing with production of the pylon segments. At least expenditure on logistics and organization increases considerably.
To produce concrete pylon parts, that is to say concrete segments, namely precast concrete parts, concrete shutterings are used, which form a cavity into which the concrete is poured. A corresponding reinforcement is also provided therein and, after the concrete has set, it is removed from the shuttering and then subjected to further processing. An inner and an outer shuttering can be used for production of frustoconical pylon segments or corresponding segment portions. Accordingly an inner and an outer shuttering are required. After the concrete has set the outer shuttering which can weigh 5 t to 10 t can be lifted away by means of a crane so that the hardened precast concrete part is accessible and can be transported in turn by means of a crane for further processing. That operation is complicated and expensive and requires a high degree of involvement of correspondingly heavy machines, which in turn increases the effort involved in production and makes production more expensive.
In that respect finally the pylon segments are to be transported by means of a flat-bed truck from the production factory which produced the pylon segments in the form of precast concrete parts, to the respective location for erection of a wind power installation so that a concrete pylon of a wind power installation can be set up there by means of those pylon segments.
As such segments are substantially in the shape of a truncated cone casing or a segment of a truncated cone casing they give rise to particular problems upon transportation on such a flat-bed truck. In that case the precast concrete parts are usually to be transported in the standing position because that requires the smallest amount of space when they are being transported. Concrete segments are sometimes produced as large as possible, but nonetheless so small that they can still be transported on road. In that respect generally permissible maximum dimensions apply. A particular requirement is that such a large pylon segment or a plurality thereof are to be securely and safely transported on the road by means of a flat-bed truck. If they are not sufficiently tightly strapped down by mistake there is the risk that in a bend they tip off the low-bed truck or undesirably slide around when the truck brakes. That can occur in particular when the pylon segment is strapped down by strapping which can come loose by virtue of slight slippage because of the rounded configurations of the respective pylon segment.